# trans not OK (dTARG; TARG = sv_newmortal();)
# ucfirst etc not OK: TMP arg processed inplace
# quotemeta not OK (unsafe when TARG == arg)
-# each repeat not OK too due to array context
+# each repeat not OK too due to list context
# pack split - unknown whether they are safe
# sprintf: is calling do_sprintf(TARG,...) which can act on TARG
# before other args are processed.